1. Field of Invention
This invention relates to the field of boat trailers. More specifically, the invention comprises a skid assembly which may be attached to the frame of a boat trailer just forward of the wheels. The purpose of the skid assembly is to prevent the boat trailer wheel from dropping abruptly off the end of a ramp, thereby causing the trailer to become stuck.
2. Description of Prior Art
Boat trailers are well known in the prior art. They commonly have two dominant principles guiding their design: (1) they must carry the boat securely as it is towed down the highway, and (2) they must facilitate the launching and recovery of the boat, typically using a concrete ramp. It is this second concern which often proves the most daunting challenge.
Boat launching ramps must be fairly steep, typically having a grade between 5% and 9%. This results from the fact that the trailer must be sufficiently submerged to float the boat free while the car or truck is still on dry ground. The steep grade causes difficulty when the boat is recovered and the car or truck attempts to pull it up the ramp.
FIG. 1 illustrates a typical prior art trailer. Trailer 10 has primary elements trailer frame 12, hitch 14, and wheels 16. FIG. 2 illustrates trailer 10 positioned on ramp 18. The vehicle towing trailer 10 is not illustrated, although persons skilled in the art will readily comprehend that the towing vehicle is attached to trailer 10 at hitch 14. As shown, wheel 16 has slipped over ramp end 20. Ramp end 20 is an abrupt edge commonly found on the end of concrete ramps, especially in coastal regions where the sand bottom is scoured away from the ramp by wave and tidal actions. Ideally, trailer 10 would not be backed far enough to place wheel 16 over the end of ramp 18. However, when the water is lowxe2x80x94such as near the time of low tidexe2x80x94the user must back trailer 10 to this point in order to get enough water over trailer 10 to recover the boat. FIG.2 illustrates a common situation where the sand or mud immediately off the end of ramp 18 has been scoured away by wave and propeller action. This phenomenon obviously worsens the problem described.
The reader will easily appreciate that once the boat is loaded on trailer 10 in this position, wheel 16 will be pulled forward against ramp end 20 as the towing vehicle attempts to pull trailer 10 up the ramp. Ramp end 20 acts as a wheel chock, making it very difficult to extract trailer 10. In addition, trailer 10 may actually be resting on the concrete surface, introducing further resistance to forward motion.
Several prior art inventions have attempted to generally remedy this concern. U.S. Pat. No. 5,228,713 to Kovach (1993) discloses a pivoting trailer which allows the boat to remain partially supported by the water as the trailer advances up the ramp. The primary purpose of the Kovach device is to properly position the boat over the trailer frame, with the result that the trailer may be safely placed in deeper water. It does not, however, directly address the objective of the present invention. In addition, the Kovach device is quite complex, requiring a moving assembly capable of guiding and supporting an object as heavy as a boat. This added complexity necessarily entails greater expense in the manufacturing of the trailer.
A simpler approach is disclosed in U.S. Pat. No. 4,895,347 to Anderson (1990). The Anderson device uses starting ramps placed on the launching ramp itself. These starting ramps allow the towing vehicle a short starting run in which the rear axle is not moving uphill. The Anderson device also discloses a system of chains and springs which are used to anchor the mobile ramps in position. Of course, the ramps must be carefully placed as the trailer is being backed into the water. This requirement means that either two persons are needed, or the vehicle driver must repeatedly stop and exit the vehicle. In addition, the use of large springs in the device introduces a safety hazard because they will store energy as they are extended.
The known devices for aiding the recovery of a boat trailer are therefore limited in that they:
1. Require the use of a large moveable assembly on the boat trailer;
2. Are expensive to produce;
3. Require the vehicle driver to repeatedly stop and exit the vehicle; and
4. Introduce a safety hazard.
Accordingly, several objects and advantages of the present invention are:
1. To eliminate the use of any moveable assemblies on the trailer;
2. To provide a relatively inexpensive device;
3. To provide a device which does not require the driver to stop and exit the vehicle; and
4. To provide a device which does not use springs or other energy storage devices which could introduce a safety hazard.